U.S. patent number 6,966,944 [Application Number 10/874,266] was granted by the patent office on 2005-11-22 for anticurling agent, ink jet ink, method for ink jet recording and method for reducing curling.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Hirofumi Ichinose, Minako Kawabe, Yutaka Kurabayashi, Hiromichi Noguchi, Masako Shimomura, Kenji Shinjo.
United States Patent |
6,966,944 |
Shimomura , et al. |
November 22, 2005 |
Anticurling agent, ink jet ink, method for ink jet recording and
method for reducing curling
Abstract
The present invention provides an anti-curl agent containing an
amide compound of specific structure and molecular weight, an ink
jet ink containing the amide compound, a method for ink jet
recording to form images by ejecting the ink, and a method for
reducing curl of recording media using the ink. The anti-curl agent
of the present invention can reduce shape changes of a printed
paper with a lapse of time, i.e., the curl phenomenon, tending to
occur in particular with a plain paper printed over the entire
surface, without deteriorating image quality.
Inventors: |
Shimomura; Masako (Kanagawa,
JP), Noguchi; Hiromichi (Tokyo, JP),
Shinjo; Kenji (Kanagawa, JP), Kurabayashi; Yutaka
(Tokyo, JP), Ichinose; Hirofumi (Tokyo,
JP), Kawabe; Minako (Kanagawa, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
32684267 |
Appl.
No.: |
10/874,266 |
Filed: |
June 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCTJP0316713 |
Dec 25, 2003 |
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Foreign Application Priority Data
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Dec 26, 2002 [JP] |
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2002-378250 |
Dec 26, 2002 [JP] |
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2002-378256 |
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Current U.S.
Class: |
106/31.43;
106/31.75 |
Current CPC
Class: |
C09D
11/38 (20130101); C09D 11/54 (20130101); D21H
27/14 (20130101); B41J 11/0005 (20130101); B41J
11/0015 (20130101) |
Current International
Class: |
C09D
11/00 (20060101); D21H 27/14 (20060101); C09D
011/02 () |
Field of
Search: |
;106/31.43,31.75
;562/556,553 ;564/156,152,160,192,199,203 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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43 10 534 |
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Oct 1993 |
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DE |
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0 447 784 |
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Sep 1991 |
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EP |
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0 643 113 |
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Mar 1995 |
|
EP |
|
0 719 845 |
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Jul 1996 |
|
EP |
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0 780 450 |
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Jun 1997 |
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EP |
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57-10660 |
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Jan 1982 |
|
JP |
|
58-23992 |
|
Feb 1983 |
|
JP |
|
58-23993 |
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Feb 1983 |
|
JP |
|
58-23995 |
|
Feb 1983 |
|
JP |
|
4-211466 |
|
Aug 1992 |
|
JP |
|
6-41484 |
|
Feb 1994 |
|
JP |
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6-157955 |
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Jun 1994 |
|
JP |
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6-240189 |
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Aug 1994 |
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JP |
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7-268261 |
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Oct 1995 |
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JP |
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8-231911 |
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Sep 1996 |
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JP |
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9-176538 |
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Jul 1997 |
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JP |
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2004209762 |
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Jul 2004 |
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JP |
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2004210906 |
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Jul 2004 |
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JP |
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2004210914 |
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Jul 2004 |
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JP |
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Primary Examiner: Klemanski; Helene
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Parent Case Text
This application is a continuation of International Application No.
PCT/JP03/16713 filed on Dec. 25, 2003 which claims the benefit of
Japanese Patent Application Nos. 2002-378250 filed on Dec. 26, 2002
and 2002-378256 filed on Dec. 26, 2002.
Claims
What is claimed is:
1. An ink jet ink comprising: a colorant; an aqueous medium; and an
amide compound which has a structure selected from the group
consisting of the general formulae (a) and (b) described below, and
a molecular weight below 1000: ##STR4##
wherein, n is 1; R.sub.0 is a linear or branched alkanol group of 2
to 4 carbon atoms, --(CH.sub.2).sub.m1 COOH where m1 is 2 or 3,
--(CH.sub.2).sub.m2 SO.sub.3 Na where m2 is 2 or 3 or
--(CH.sub.2).sub.m3 SO.sub.3 H where m3 is 2 or 3; and R.sub.1 and
R.sub.2 are each independently a hydrogen atom or a linear or
branched alkanol group of 2 to 4 carbon atoms, substituted with a
hydrogen atom or hydroxyl group, where R.sub.1 and R.sub.2 are not
a hydrogen atom simultaneously, and ##STR5##
wherein, R.sub.0 is phenylene, ethylene, propylene, butylene or
cyclohexylene group; and R.sub.1 to R.sub.4 are each independently
a hydrogen atom, a linear or branched alkanol group of 2 to 4
carbon atoms or --(CH.sub.2 CH.sub.2 O).sub.n H where n is an
integer of 1 to 5, where R.sub.1 and R.sub.2 are not a hydrogen
atom simultaneously, and R.sub.3 and R.sub.4 are not a hydrogen
atom simultaneously.
2. The ink according to claim 1, wherein said amide compound is
represented by the general formula (a).
3. The ink according to claim 1, wherein said amide compound is
represented by the general formula (b).
4. A method for ink jet recording, comprising at least a step of
ejecting an ink according to claim 1 by an ink jet method.
5. A method for reducing curl of a recording medium by applying an
ink according to claim 1 to a recording medium by ejecting the ink
by an ink jet method.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anti-curl agent, an ink jet ink
containing the anti-curl agent, a method for ink jet recording to
form images by ejecting the ink, and a method for reducing curl of
the recording medium using the ink.
2. Related Background Art
Ink jet recording method ejects ink droplets directly onto a
water-absorptive medium like paper, to which the ink is attached to
form images thereon. Because the ink-jet printer is compact and low
cost, it is widely used as the output machine of the personal
computers at home and offices. Moreover, an ink jet recording
method is suitably applicable for recording an image with high
resolution and quality at a high speed.
The ink for this type of recording method generally comprises water
as a major component, a colorant, and a polar solvent such as
glycerin to prevent ink deposition to the fine nozzles. Such an ink
has advantages of being odorless and having a high flash point.
However, when a large quantity of the ink is applied to a recording
medium to form an image with the colorant in the ink, a large
quantity of water may be absorbed by the recording medium because
the component of the ink is mostly water. As a result, the printing
speed sometimes depends on the penetration speed of the ink into
the recording medium.
On the other hand, when plain paper is used as a recording medium,
the shape may change after absorbing a large quantity of water.
There are two general categories in these changes; one is cockling
and the other curl. The curl phenomenon means shift of the paper
edge towards the center of the printed side or the backside. Curl
to the backside is referred to as reverse curl. Curl may occur
immediately after printing or may appear with a lapse of time.
Eventually the paper may become cylindrical in an extreme case, and
storage of the recording media becomes very inconvenient.
Some attempts have been made to solve these problems. For example,
Japanese Unexamined Patent Publication No. H06-240189 discloses a
technique to reduce the curl phenomenon by adding 4 to 20% by mass
of sugar to the ink.
Japanese Unexamined Patent Publication No. H06-157955 discloses the
compounds having multiple hydroxyl groups as the anti-curl agent.
These compounds include diols of 3 to 11 carbon atoms and ethylene
oxide or polyoxyalkylene derivatives thereof, ethylene oxide or
polyoxyalkylene derivatives of glycerin, pyranosides and
derivatives thereof, and polyoxyalkylene derivatives of aliphatic
polyamine.
Japanese Unexamined Patent Publication No. H09-176538 discloses an
anti-curl agent of a carboxylic acid amide, e.g., acetamide,
propionamide, isobutylamide or hexanamide; alkylurea of up to 6
carbon atoms, e.g., butylurea, 1,3-dimethylurea, ethylurea,
propylurea or 1,3-diethylurea; or nitrogen-containing cyclic
compound, e.g., tetrahydropyrimidone or imidazolidinone, to be
incorporated in an ink at least 10% by mass or more.
SUMMARY OF THE INVENTION
The inventors of the present invention have found out that the ink
compositions disclosed by the above-described prior art are not
desirable. The ink disclosed by JP H06-240189 may have deteriorated
ejectability, when used for thermal ink jet printing, because it
tends to cause kogation on the heater. The ink disclosed by JP
H06-157955 shows insufficient anti-curl effect. The anti-curl agent
disclosed by JP H09-176538 may be easily hydrolyzed into an
alkylamine.
Therefore, there are still demands for preventing curl of plain
paper more effectively after images are printed thereon with an
aqueous ink jet ink at a high recording density (i.e., with a large
quantity of ink per unit area).
The object of the present invention is to provide an anti-curl
agent that can reduce shape changes of a printed paper (curl
phenomenon) which tends to occur in particular when a plain paper
is printed over the entire surface without deteriorating image
quality. Another object is to provide an ink jet ink containing the
anti-curl agent. Still another object is to provide a method for
ink jet recording to form images by ejecting the ink. It is still
another object to provide a method for reducing curl of recording
media using the ink.
The present invention relates to an anti-curl agent for the
recording medium, comprising an amide compound which has a
structure selected from the group consisting of the general
formulae (a), (b) and (c) described below, and a molecular weight
less than 1000: ##STR1##
(wherein, R.sub.0 is a linear or branched alkanol group of 2 to 4
carbon atoms, --(CH.sub.2).sub.n1 COOH (n1 is 2 or 3),
--(CH.sub.2).sub.n2 SO.sub.3 Na (n2 is 2 or 3) or
--(CH.sub.2).sub.n3 SO.sub.3 H (n3 is 2 or 3); and R.sub.1 and
R.sub.2 are each independently a hydrogen atom or a linear or
branched alkanol group of 2 to 4 carbon atoms, where R.sub.1 and
R.sub.2 are not a hydrogen atom simultaneously); ##STR2##
(wherein, R.sub.0 is a linear or branched alkanol group of 2 to 4
carbon atoms, --(CH.sub.2).sub.m1 COOH (m1 is 2 or 3),
--(CH.sub.2).sub.m2 SO.sub.3 Na (m2 is 2 or 3) or
--(CH.sub.2).sub.m3 SO.sub.3 H (m3 is 2 or 3); and R.sub.1 and
R.sub.2 are each independently a hydrogen atom or a linear or
branched alkanol group of 2 to 4 carbon atoms, substituted with a
hydrogen atom or hydroxyl group, where R.sub.1 and R.sub.2 are not
a hydrogen atom simultaneously); and ##STR3##
(wherein, R.sub.0 is a phenylene, ethylene, propylene, butylene or
cyclohexylene group; and R.sub.1 to R.sub.4 are each independently
a hydrogen atom, a linear or branched alkanol group of 2 to 4
carbon atoms or --(CH.sub.2 CH.sub.2 O).sub.n H (n is an integer of
1 to 5), where R.sub.1 and R.sub.2 are not a hydrogen atom
simultaneously, and R.sub.3 and R.sub.4 are not a hydrogen atom
simultaneously.
The present invention also relates to an ink-jet ink containing a
colorant and an aqueous medium, the ink having an amide compound
which has a structure selected from the group consisting of the
general formulae (a), (b) and (c) described above, having a
molecular weight below 1000.
The present invention also relates to a method of ink jet
recording, comprising at least a step of discharging the above ink
by an ink jet method.
The present invention also relates to a method for reducing curl of
a recording medium by applying the above ink thereto by an ink jet
recording method.
The anti-curl agent of the present invention, even when an image is
formed with an aqueous ink jet ink on a plain paper, sufficiently
prevents the curl phenomenon without lowering the quality of image,
and enables easy handling of the recorded matter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an oblique view which outlines a major section of one
embodiment of an ink jet printer; and
FIG. 2 is a schematic cross-sectional view of the major part of a
recording apparatus to use the anti-curl agent of the present
invention as an underprinting agent.
DETAILED DESCRIPTION OF THE INVENTION
First, the amide compound having an anti-curl effect for the
present invention and the anti-curl effect of the ink-jet ink
containing the compound are described.
The inventors of the present invention considered that the curl
phenomenon of a recording medium occurred because the cellulose
fibers constituting the recording medium swelled when hydrogen
bonds were formed between water and hydroxyl groups of cellulose
and then shrank as the water evaporates. The inventors predicted
that the curl phenomenon of a recording medium could be well
prevented by incorporating in an ink a compound having two or more,
preferably three or more groups in the molecule which could bind to
cellulose via hydrogen bonding better than the water molecules
could. Thus the present invention was made.
The amide compound represented by one of the general formulae (a)
to (c) is considered to exhibit an excellent anti-curl effect,
because the proton in the hydroxyl group of alkanol group, the
proton in the terminal hydroxyl group of ethylene oxide group, or
the terminal proton of carboxyl or sulfone group binds to oxygen of
the hydroxyl group of cellulose through hydrogen bonding, to
crosslink the fibers, where the alkanol, ethylene oxide, carboxyl
or sulfone group is directly linked to the amide bond. Moreover,
nucleophilicity of the nitrogen atom in the amide bond works to
strengthen the hydrogen bond formed between the cellulose
molecules. As a result, the synergistic effect of the proton and
the nitrogen atom is considered to further improve the anti-curl
effect of the amide compound.
Still more, the amide compound containing two or more amide bonds
in the molecular structure can exhibit a higher anti-curl effect by
having at least one alkanol or ethylene oxide group for each
nitrogen atom.
On the other hand, when the amide compound contains only one
nitrogen atom, which forms an amide bond with carbonyl group in the
molecular structure, it cannot exhibit a sufficient anti-curl
effect unless at least one alkanol or ethylene oxide group is
directly bonded to the nitrogen atom and an alkanol or ethylene
oxide group is simultaneously bonded to the carbon atom of the
carbonyl group constituting the amide bond. For still higher
anti-curl effect, it is preferable for the amide compound to have
two alkanol or ethylene oxide groups each directly bonded to the
nitrogen atom constituting the amide bond and one alkanol or
ethylene oxide group directly bonded to the carbon atom in the
amide bond, in order to crosslink the cellulose fibers with three
hydrogen bonds.
The mechanism of the present invention is considered applicable to
compounds other than the amide compounds of the present invention.
In other words, a compound having an urethane or urea bond can work
as an anti-curl agent by the nucleophilic function of the nitrogen
atom in the bond, when 2 to 4 alkyl alcohol molecules of 4 or less
carbon atoms are directly bonded to the urethane or urea bond.
Compounds having such a urea bond include
1,3-bis(.beta.-hydroxyethyl)urea,
1-.alpha.-hydroxypropyl-3-(.beta.-hydroxyethyl)urea,
1,1-bis(.beta.-hydroxyethyl)-3-(.beta.-hydroxyethyl)urea and
1,1-bis(.gamma.-hydroxypropyl)-3-(.beta.-hydroxyethyl)urea, as
disclosed by Japanese Patent No. 3,412,857. Compounds having such a
urethane bond include hexamethylenediamine to which an isocyanate
derivative is added, as disclosed in Japanese Unexamined Patent
Publication No. H07-268261. The amide compound for the present
invention and the above-described known compounds have two or more
nitrogen-containing atomic groups (urea, urethane or amide bond),
and exhibit an excellent anti-curl effect probably resulting from a
strong agglomerating force between the atomic groups themselves, or
between the atomic groups and hydroxyl group in the cellulose
molecule.
On the other hand, it is considered that urea is too small to
cross-link the cellulose molecules and is considered to be
difficult to crosslink two or more cellulose fibers, although it
has amide bond, and actually, it does not exhibit anti-curl effect.
When methanol is the alkanol group which bonds directly to the
amide bond, the compound becomes so reactive that the storage
stability of the ink becomes deteriorated.
Alkanol groups having 2 to 4 carbon atoms are preferable because
the nitrogen atom in the amide bond preferably has a certain
nucleophilicity, while alkanol groups having more than 4 carbon
atoms are not preferable because strength of hydrogen bonding with
cellulose fiber owing to the nucleophilic function of the nitrogen
will decrease. The most preferable alkanol group is alkanol of two
carbon atoms, i.e., ethanol.
When ethylene oxide is the functional group directly bonded to the
nitrogen atom of the amide bond, it is preferably a polymer of 1 to
5 ethylene oxide molecules. Polymers longer than 5 ethylene oxide
units are not preferable because insufficient nucleophilicity of
the nitrogen atom results in low anti-curl effect and the high
viscosity of the compound increases ink viscosity resulting in
deteriorated ink ejectability, in particular, after a certain
period of suspension of ejection.
The amide compound for the anti-curl agent of the present invention
has a molecular weight below 1000. An amide compound having
molecular weight of 1000 or more is not preferable, because the ink
becomes so viscous that flowability of the ink is lost and that
evaporation of water and/or the low-boiling-point solvent
particularly occurs at the meniscus on the nozzle, resulting in
clogging of the nozzle.
Therefore, the anti-curl agent for the present invention contains
an amide compound which has a structure selected from the group
consisting of the general formulae (a), (b) and (c) described
above, with alkanol or ethylene oxide group directly bonded to the
amide bond, and a molecular weight below 1000.
In the general formula (a), R.sub.0 is a linear or branched alkanol
group of 2 to 4 carbon atoms, --(CH.sub.2).sub.n1 COOH (n1 is 2 or
3), --(CH.sub.2).sub.n2 SO.sub.3 Na (n2 is 2 or 3) or
--(CH.sub.2).sub.n3 SO.sub.3 H (n3 is 2 or 3). The preferable
examples include --CH.sub.2 CH.sub.2 OH, CH.sub.2 CH(CH.sub.3)OH,
CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 OH, --CH.sub.2 CH.sub.2
CH(CH.sub.3)OH, CH.sub.2 CH(CH.sub.3)CHOH, --CH.sub.2 CH.sub.2
COOH, --CH.sub.2 CH.sub.2 CH.sub.2 COOH, CH.sub.2 CH(CH.sub.3)COOH,
--CH.sub.2 CH.sub.2 SO.sub.3 Na, --CH.sub.2 CH.sub.2 CH.sub.2
SO.sub.3 Na, CH.sub.2 CH(CH.sub.3)SO.sub.3 Na, --CH.sub.2
CH(CH.sub.3)SO.sub.3 H, --CH.sub.2 CH.sub.2 SO.sub.3 H and
--CH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 H.
In the general formula (a), R.sub.1 and R.sub.2 are each
independently a hydrogen atom or an alkanol group. The preferable
alkanol groups for the present invention include --CH.sub.2
CH.sub.2 OH, --CH.sub.2 CH.sub.2 CH.sub.2 OH, --CH.sub.2 CH.sub.2
CH.sub.2 CH.sub.2 OH, --(CH.sub.2)CH(CH.sub.3)OH, --CH.sub.2
CH.sub.2 CH(CH.sub.3)OH, --CH.sub.2 CH(CH.sub.3)CH.sub.2 OH,
--CH(OH)CH.sub.2 CH.sub.3, --CH(OH)CH.sub.2 CH.sub.2 CH.sub.3,
--CH.sub.2 C(CH.sub.3)(OH)CH.sub.3, --CH(OH)CH.sub.3,
--CH(CH.sub.3)CH.sub.2 OH, --C(CH.sub.3).sub.2 OH, --CH.sub.2
CH(OH)CH.sub.2 CH.sub.3, --CH(CH.sub.3)CH.sub.2 CH.sub.2 OH,
--CH(CH.sub.3)CH(OH)CH.sub.3, --C(CH.sub.3).sub.2 CH.sub.2 OH,
--CH(OH)CH(CH.sub.3)CH.sub.3 and --C(OH) (CH.sub.3)CH.sub.2
CH.sub.3.
In the general formula (b), R.sub.0 is a linear or branched alkanol
group of 2 to 4 carbon atoms, --(CH.sub.2).sub.m1 COOH (m1 is 2 or
3), --(CH.sub.2).sub.m2 SO.sub.3 Na (m2 is 2 or 3) or
--(CH.sub.2)m.sub.3 SO.sub.3 H (m3 is 2 or 3). The preferable
examples include --CH.sub.2 CH.sub.2 OH, CH.sub.2 CH(CH.sub.3)OH,
CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 OH, --CH.sub.2 CH.sub.2
CH(CH.sub.3)OH, CH.sub.2 CH(CH.sub.3)CHOH, --CH.sub.2 CH.sub.2
COOH, --CH.sub.2 CH.sub.2 CH.sub.2 COOH, CH.sub.2 CH(CH.sub.3)COOH,
--CH.sub.2 CH.sub.2 SO.sub.3 Na, --CH.sub.2 CH.sub.2 CH.sub.2
SO.sub.3 Na, CH.sub.2 CH(CH.sub.3)SO.sub.3 Na, --CH.sub.2
CH(CH.sub.3)SO.sub.3 H, --CH.sub.2 CH.sub.2 SO.sub.3 H and
--CH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 H.
In the general formula (b), R.sub.1 and R.sub.2 are each
independently a hydrogen atom or an alkanol group. The preferable
alkanol groups for the present invention include --CH.sub.2
CH.sub.2 OH, --CH.sub.2 CH.sub.2 CH.sub.2 OH, --CH.sub.2 CH.sub.2
CH.sub.2 CH.sub.2 OH, --(CH.sub.2)CH(CH.sub.3)OH, --CH.sub.2
CH.sub.2 CH(CH.sub.3)OH, --CH.sub.2 CH(CH.sub.3)CH.sub.2 OH,
--CH(OH)CH.sub.2 CH.sub.3, --CH(OH)CH.sub.2 CH.sub.2 CH.sub.3,
--CH.sub.2 C(CH.sub.3)(OH)CH.sub.3, --CH(OH)CH.sub.3,
--CH(CH.sub.3)CH.sub.2 OH, --C(CH.sub.3).sub.2 OH, --CH.sub.2
CH(OH)CH.sub.2 CH.sub.3, --CH(CH.sub.3)CH.sub.2 CH.sub.2 OH,
--CH(CH.sub.3)CH(OH)CH.sub.3, --C(CH.sub.3).sub.2 CH.sub.2 OH,
--CH(OH)CH(CH.sub.3)CH.sub.3 and --C(OH) (CH.sub.3)CH.sub.2
CH.sub.3.
In the general formula (c), R.sub.0 is phenylene, ethylene,
propylene, butylene or cyclohexylene group, of which phenylene,
propylene, butylene and cyclohexylene group are more preferable.
When R.sub.0 is phenylene or cyclohexylene group, it may be
substituted at any of ortho, meta or para position.
In the general formula (c), the four functional groups of R.sub.1
to R.sub.4 are each independently a hydrogen atom, a linear or
branched alkanol group of 2 to 4 carbon atoms or --(CH.sub.2
CH.sub.2 O).sub.n H (n is an integer of 1 to 5), where R.sub.1 and
R.sub.2 are not a hydrogen atom simultaneously, and R.sub.3 and
R.sub.4 are not a hydrogen atom simultaneously. The preferable
alkanol groups include --CH.sub.2 CH.sub.2 OH, --CH.sub.2 CH.sub.2
CH.sub.2 OH, --CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 OH,
--(CH.sub.2)CH(CH.sub.3)OH, --CH.sub.2 CH.sub.2 CH(CH.sub.3)OH,
--CH.sub.2 CH(CH.sub.3)CH.sub.2 OH, --CH(OH)CH.sub.2 CH.sub.3,
--CH(OH)CH.sub.2 CH.sub.2 CH.sub.3, --CH.sub.2
C(CH.sub.3)(OH)CH.sub.3, --CH(OH)CH.sub.3, --CH(CH.sub.3)CH.sub.2
OH, --C(CH.sub.3).sub.2 OH, --CH.sub.2 CH(OH)CH.sub.2 CH.sub.3,
--CH(CH.sub.3)CH.sub.2 CH.sub.2 OH, --CH(CH.sub.3)CH(OH)CH.sub.3,
--C(CH.sub.3).sub.2 CH.sub.2 OH, --CH(OH)CH(CH.sub.3)CH.sub.3 and
--C(OH)(CH.sub.3)CH.sub.2 CH.sub.3. The preferable (CH.sub.2
CH.sub.2 O).sub.n H (n is an integer of 1 to 5) include --CH.sub.2
CH.sub.2 OH, --(CH.sub.2 CH.sub.2 O).sub.2 H, --(CH.sub.2 CH.sub.2
O).sub.3 H, --(CH.sub.2 CH.sub.2 O).sub.4 H and --(CH.sub.2
CH.sub.2 O).sub.5 H. Each of R.sub.1 to R.sub.4 is preferably a
hydrogen atom, or a linear or branched alkanol group of 2 to 4
carbon atoms. When R.sub.1 to R.sub.4 are each --(CH.sub.2 CH.sub.2
O).sub.n H (n is an integer of 1 to 5), it is preferable that
R.sub.1 and R.sub.3 are each --(CH.sub.2 CH.sub.2 O).sub.n H (n is
an integer of 2 to 5), and R.sub.2 and R.sub.4 are each
independently a hydrogen atom or --(CH.sub.2 CH.sub.2 O).sub.n H (n
is an integer of 1 to 5).
Table 1 gives the particularly preferable examples of amide
compounds.
TABLE 1 Examples of amide compounds General No. formula R.sub.0
R.sub.1 R.sub.2 R.sub.3 R.sub.4 1 (a) --CH.sub.2 CH.sub.2 COOH
--CH.sub.2 CH.sub.2 OH --CH.sub.2 CH.sub.2 OH -- -- 2 (b)n = 1
--CH.sub.2 CH.sub.2 OH --CH.sub.2 CH.sub.2 OH --CH.sub.2 CH.sub.2
OH -- -- 3 (c) Phenylene --CH.sub.2 CH.sub.2 OH --CH.sub.2 CH.sub.2
OH --CH.sub.2 CH.sub.2 OH --CH.sub.2 CH.sub.2 OH 4 (c) Propylene
--CH.sub.2 CH.sub.2 OH --H --CH.sub.2 CH.sub.2 OH --H 5 (c)
Butylene --CH.sub.2 CH.sub.2 OH --H --CH.sub.2 CH.sub.2 OH --H 6
(c) Phenylene --(CH.sub.2 CH.sub.2 O).sub.2 H --H --(CH.sub.2
CH.sub.2 O).sub.2 H --H 7 (c) Cyclohexylene --(CH.sub.2 CH.sub.2
O).sub.3 H --(CH.sub.2 CH.sub.2 O).sub.3 H --(CH.sub.2 CH.sub.2
O).sub.3 H --(CH.sub.2 CH.sub.2 O).sub.3 H 8 (c) Phenylene
--(CH.sub.2 CH.sub.2 O).sub.4 H --(CH.sub.2 CH.sub.2 O).sub.4 H
--(CH.sub.2 CH.sub.2 O).sub.4 H --(CH.sub.2 CH.sub.2 O).sub.4 H
The anti-curl agent of the present invention contains at least an
amide compound described above and it may further contain a solvent
selectable from a wide variety as required. For example, the
anti-curl agent may be solely composed of the amide compound
described above, or it may further contain any component of ink
except for the colorant, e.g., water, solvents or additives.
Preferably, the anti-curl agent of the present invention contains
the above-described amide compound at 5 to 100% by mass based on
the whole composition. When the anti-curl agent is used as a
solution, in particular for underprinting for an ink as described
later, the amide compound is preferably incorporated at 5 to 50% by
mass.
Next, the preferred embodiments of the ink of the present invention
for ink jet recording are described.
The ink of the present invention contains at least a colorant, an
aqueous solvent and at least one of the above-described amide
compounds. The present invention preferably contains the amide
compound(s) at 3 to 30% by mass, particularly preferably 3 to 10%.
At below 3%, the effect of the present invention may not be fully
exhibited. At above 10%, on the other hand, the ink tends to have
deteriorated ejectability because of excessive viscosity.
The preferred concentration of the above-described amide compound
in the ink may vary with the type and the content of other
components. The anti-curl effect tends to be hindered when a
compound having OH group and a small number of carbon atoms, e.g.,
glycerin, ethylene glycol, diethylene glycol, ethyl alcohol or
propyl alcohol is present in a large amount, although the reason is
not fully understood.
Therefore, the ink preferably contains a compound having 6 or less
carbon atoms and three or less OH groups at 10% by mass or less
based on the whole ink composition. Polar solvents having no proton
donating capacity, e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone,
sulfolane, dimethylsulfoxide or dimethylformamide, cause curl of
the recording medium to a lesser extent than the polar solvent
described above does, but curl tends to occur with a lapse of time.
Moreover, the above solvent tends to dissolve materials
constituting the ink jet head. Thus such a solvent is preferably
incorporated at 10% by mass or less based on the whole ink
composition, particularly preferably 5% by mass or less.
On the other hand, diols of 5 to 6 carbon atoms, e.g.,
1,5-pentanediol, 1,2-pentanediol, 1,2-hexanediol, 1,6-hexanediol
and 1,5-hexanediol, and ethylene glycols of 4 carbon atoms or more
also exhibit a certain anti-curl effect, although not so effective
as the amide compound in the present invention. Therefore, when one
or more of diols of 5 to 6 carbon atoms and ethyleneglycols of 4
carbon atoms are used with the anti-curl agent of the present
invention, the ink properties as the ink jet ink, such as anti-curl
effect, nozzle restoration and solubility for dyes, are
improved,
In the present invention, the total amount of the amide compound
and a solvent for preventing solidification of the ink and thereby
nozzle clogging resulting from evaporation of the water component
may be 10 to 50% by mass based on the total mass of the ink
composition, particularly preferably 10 to 30%.
The colorant for the present invention is not specifically limited,
and may be a dye or a pigment. Various dyes and pigments can be
used for the present invention without causing problems. Dyes and
pigments of orange, green, blue, dark yellow, gray and violet
colors may be used, in addition to those of black, cyan, yellow and
magenta colors.
Dyes for the present invention are preferably acidic dyes, basic
dyes, direct dyes, food dyes, disperse dyes and reactive dyes. Such
a dye or pigment is incorporated preferably at 0.01 to 10% by mass
based on the whole ink composition. Also a pigment dispersion
dispersed by a dispersant such as a resin or a surfactant, or a
self-dispersing pigment subjected to surface-modification to have
ionic properties on the surface, can be used in the present
invention. The pigment particles should be sufficiently fine,
because the ink composition where they are dispersed is ejected
through a fine nozzle orifice in the ink jet head. They are
preferably 50 to 500 nm in particle size, because excessively fine
particles may deteriorate coloring power because of increased light
transmittance.
The ink composition of the present invention may contain an
inorganic pigment, e.g., silica, alumina or titania, depending on
the use.
One of the preferable aqueous media for the present invention is
water. Water is preferably incorporated at 10 to 90% by mass based
on the whole ink composition, particularly preferably 30 to 80% by
mass.
The ink of the present invention may contain a colorant, an aqueous
medium and a solvent or surfactant conventionally known for ink jet
inks.
Moreover, it may further contain a conventionally known anti-curl
agent for ink jet ink as long as the remarkable effect of the
present invention can be exhibited.
The additives useful for the present invention include a pH
adjusting agent, e.g., inorganic alkali, alkanol amine, and organic
and inorganic acid; a pH stabilizer (buffer), e.g., lithium
acetate, ammonium acetate, ammonium sulfate and
trishydroxyaminomethane; a surfactant for controlling the rate at
which the ink is absorbed by a recording medium; a fungicide for
inhibiting growth of fungi or the like in the ink during long time
storage; a chelating agent, e.g., ethylenediamine tetraacetate, for
capturing metal ions that have dissolved in the ink and may deposit
on the heater and the orifice face of the head to deteriorate
printing functions; and citric acid or the like which forms a
complex with such metal ions.
Besides, in order to reduce bleeding in the boundary between the
color ink and black ink, a black ink of the present invention and a
color ink of the present invention further containing a polyvalent
metal salt may be concomitantly used in the following manner to
agglomerate the coloring material of the black ink and enhance
fixation of the black ink: first the color ink is applied to the
recording medium and then the black ink is applied to the same
region (underprinting), or first the black ink is applied to the
recording medium and then the color ink is applied to the same
region (overprinting), or both underprinting and overprinting are
carried out. The polyvalent metal ions useful for the present
invention include Zn.sup.2+, Mg.sup.2+, Ca.sup.2+, Cu.sup.2+,
Co.sup.2+, Ni.sup.2+, Fe.sup.2+, La.sup.3+, Nd.sup.3+, Y.sup.3+ and
Al.sup.3+, although not limited thereto. The preferable anions for
binding the above ions include NO.sup.3-, F.sup.-, Cl.sup.-,
Br.sup.-, I.sup.-, CH.sub.3 COO.sup.- and SO.sub.4.sup.2-.
Another method for reducing bleeding in the boundary region between
color ink and black ink is to incorporate an organic acid in the
color ink of the present invention to make pH difference between
the inks. Such a color ink can be used for underprinting and/or
overprinting to agglomerate the colorant in the black ink and
thereby accelerate fixation of the black ink. The preferable
organic acids for the present invention include dibasic acids,
e.g., oxalic, succinic, malonic, gluconic and adipic acids, formic,
acetic and propionic acids.
Alternatively, a second, transparent ink containing a gelling agent
for gelling the colorant of the ink of the present invention may be
used for underprinting or overprinting to accelerate gelling of the
colorant in the ink. The gelling agents useful for the present
invention include cationic components, e.g., the polyvalent metal
salts described above, organic acids also described above,
polyallylamine, polyethyleneimine and benzalconium chloride. The
gelling agents useful for the present invention are not limited to
the above, and any one may be used so long as it can agglomerate
the colorant.
Underprinting or overprinting tends to use ink more, causing more
curl of the printed matter. However, curl of a printed medium can
be very effectively prevented with a colorant-free gelling solution
containing an anti-curl agent of the present invention, as well as
the ink containing an anti-curl agent of the present invention.
The ink containing the gelling agent described above may be applied
by using an ink jet head, or spread over the entire surface of a
recording medium by using a bar coater or a spray coater.
Needless to say, the anti-curl agent of the present invention, when
used as an underprinting (preprinting) solution, can exhibit an
anti-curl effect for the recording medium if it does not have a
function to agglomerate the colorant.
The ink of the present invention, when used for ink jet printing,
may contain a surfactant to accelerate ink penetration/fixation to
the recording medium, or speed up recording. The surfactant useful
for the present invention may be anionic or cationic, but is
preferably nonionic in consideration of ink storage stability. More
specifically, the preferable surfactants for the present invention
are those based on polyoxyethylene alkyl ether, polyoxyethylene
alkyl ester, Pluronic type ethylene oxide and propylene oxide,
acetylene glycol/ethylene oxide adduct, dimethyl siloxane/ethylene
oxide adduct and derivatives thereof, and betaine type alkyl
fluoride, of which polyoxyethylene alkyl ether and acetylene
glycol/ethylene oxide adduct are more preferable in consideration
of storage stability for extended periods and surfactant activity
effect.
As discussed in Japanese Patent No. 3,412,857, a structure having a
hydrogen added to the amide bond tends to be hydrolyzed by the
action of the active hydrogen to generate an alcohol amine such as
ethanolamine, causing pH increase. The inventors of the present
invention have calculated the relationship between the
monoethanolamine content in a solution and pH of the solution using
the dissociation constant (K) of monoethanolamine. When the
monoethanolamine content was 1.0.times.10.sup.-4 mol/L, pH was
9.62, and pH 8.90 at 1.0.times.10.sup.-5 mol/L. Therefore it is
also preferable for the present invention to control the content of
alcohol amine derived from the starting material, and to control pH
of the solution, to repress amine activity.
The present invention is particularly effective for a recording
medium of a sheet-type plain paper. The plain paper includes those
commercially available papers such as copy paper, recycled copy
paper, plain paper for ink jet printing, plain paper for color ink
jet printing, plain paper for ink jet/electrophotographic printing,
and Japanese paper, including those not coated with a special white
pigment on the surface, or lightly coated ones partly exposing pulp
fibers of the base paper.
The present invention is particularly suitable for the ink jet
recording method, which ejects ink droplets onto a recording medium
utilizing thermal energy. However, the present invention is also
applicable to other ink jet printing systems or writing
utensils.
A recording apparatus suitable for recording with the ink of the
present invention ejects ink droplets by applying thermal energy to
the ink held in the recording head in accordance with the recording
signals.
FIG. 1 is an oblique view of an example ink jet printer having a
liquid-ejecting head of a stem where a bubble formed in the liquid
communicates with the atmosphere to eject a droplet, where, 1006:
movement-driving unit, 1008: casing, 1010: recording unit, 1010a:
carriage member, 1012: cartridge, 1012 Y, M, C and B: cartridges
for respective colors, 1014: scanning rail, 1016: belt, 1018:
motor, 1020: driving unit, 1022a and 1022b: roller units, 1024a and
1024b: roller units, 1026: recovery unit, 1026a and 1026b: pulleys,
1028: recording paper, and 1030: conveying unit.
Referring to FIG. 1, in the ink jet printer, the conveying unit
1030 is held in the longitudinal direction in the casing 1008 and
intermittently conveys a recording medium or paper 1028 in the
direction of arrow P shown in FIG. 1; recording unit 1010 is
reciprocally moved almost in parallel to the direction S along the
scanning rail 1014 which is almost orthogonal to the direction P,
and movable driving unit 1006 as a driving means for reciprocally
moving the recording unit 1010.
The conveying unit 1030 comprises two pairs of the roller units
1022a and 1022b and 1024a and 1024b facing each other and the
driving unit 1020 which drives each of the roller units. When the
driving unit 1020 is on, the conveying unit intermittently conveys
the paper 1028 in the direction P shown in FIG. 1 holding the paper
1028 between the roller units 1022a and 1022b, and 1024a and
1024b.
The movement-driving unit 1006 comprises the belt 1016 wound around
each of the pulleys 1026a and 1026b on each of rotational shafts
facing each other at a given distance, and the motor 1018 which
drives the belt 1016 in both directions which is connected to the
carriage member 1010a of the recording unit 1010 and positioned
almost in parallel to the roller units 1022a and 1022b.
When the motor 1018 is started and the belt 1016 is rotated in the
direction of arrow R, the carriage member 1010a of the recording
unit 1010 moves by a given distance in the direction of arrow S
shown in FIG. 1. When the belt 1016 is rotated in the direction
reverse to the arrow R by the motor 1018, the carriage member 1010a
of the recording unit 1010 moves by a given distance in the
direction reverse to the arrow S. Moreover, near one end of the
movement-driving unit 1006, a recovery unit 1026 is provided at a
home position for the carriage member 1010a as discharge-recovering
means for the recording unit 1010. The recovery unit 1026 is
positioned to face the ink eject ports of the recording unit
1010.
The recording unit 1010 is provided with the ink jet cartridges
(hereinafter sometimes referred to as merely cartridge) 1012Y,
1012M, 1012C and 1012B for respective colors, e.g., yellow,
magenta, cyan and black, which can be freely attached to or
detached from the carriage member 1010a.
FIG. 2 schematically illustrates a cross-sectional view of the main
part of a recording apparatus which uses the anti-curl agent of the
present invention as an underprinting (preprinting) agent, where
numeral 91 designates recording medium, 92: recording head, 93:
printing ink, 94: platen, 95: coating roller, 96: conveying roller
and 97: anti-curl agent of the present invention.
Referring to FIG. 2, the recording medium 91 is plain paper, and is
moved in the direction of the arrow, which indicates the
paper-conveying passage in the recording apparatus. The recording
head 92, which is provided in the recording apparatus, is for
printing images by scanning in the direction perpendicular to the
conveyance direction of the recording medium 91. In this figure,
the printing ink 93 is now ejected onto the paper surface. The
platen 94 is provided at the opposite side of the ejected ink 93
across the recording medium 91 to stably hold the recording medium
91 being printed with the ejected ink.
The anti-curl agent of the present invention is applied at the
position A shown in FIG. 2.
The coating roller 95, provided in the passage of the recording
medium, transfers and spreads an anti-curl agent over the recording
medium 91, making a pair with the paper-conveying roller 96 to hold
the recording medium 91 in-between. The conveying roller 96 may be
used as a device dedicated for pressurizing the coating roller 95.
Other rollers (pinch roller, spur or the like) necessary for stably
holding the recording medium 91 while an image is being formed
thereon are not shown in FIG. 2.
While the paper conveying roller 96 conveys the recording medium
91, anti-curl agent 97 supplied almost uniformly onto the coating
roller 95 by an anti-curl agent supply means (not shown) is
transferred to the recording medium. The anti-curl agent 97 is
uniformly transferred onto the recording medium 91 under a pressure
generated by the coating roller 95 and the paper-conveying roller
96.
The anti-curl agent supply means (not shown) is not limited. It may
be selected, as required, from various embodiments, e.g., means for
supplying the agent from its storage tank onto the coating roller
95, or for supplying the agent from an absorbent impregnated with
the agent onto the coating roller 95.
Moreover, the means for transferring the anti-curl agent onto the
recording medium 91 using the coating roller 95 is not limited to
the above. It may be selected, as required, from various
embodiments, e.g., means for transferring the agent from its
storage tank onto the recording medium 91 by a rubber-like spatula,
or transferring the agent from an absorbent impregnated with the
agent onto the recording medium 91.
The recording medium 91, after being coated with the anti-curl
agent 97 of the present invention, is printed with the printing ink
93 dejected from the recording head 92 at the position B shown in
FIG. 2.
The present invention is described in more detail by the Examples.
Table 2 summarizes the materials used in the Examples and the
Comparative Examples, where "part(s)" means part(s) by mass. Water
used was pure water produced by ultrafiltration, ion-exchanging
with resin or the like.
EXAMPLES
Example 1
The compounds for Example 1 given in Table 2 were mixed and
filtered by using a membrane filter (pore size: 0.2 .mu.m) to
prepare the ink of Example 1. Examples 2 to 11, Comparative
Examples 1 and 2
Inks of Examples 2 to 11, and Comparative Examples 1 and 2 were
prepared in the same manner as in Example 1, using the compounds
given in Table 2.
Example 12
(Preparation of Yellow Ink)
A styrene/acrylic acid copolymer (Joncryl 678, Johnson Polymer),
potassium hydroxide of an amount necessary for neutralizing the
copolymer and water were mixed. The resulting mixture was stirred
for mixing while it was kept at around 60.degree. C., to prepare a
10% aqueous solution of styrene/acrylic acid copolymer.
Next, the mixture was incorporated with the following components
and stirred for 30 minutes, and then dispersion-treated under the
following conditions.
10% Aqueous solution of styrene/acrylic acid 30 parts copolymer
Pigment Yellow 74 10 parts Ion-exchanged water 60 parts Dispersing
machine: Sand grinder (Imex) Milling medium: Zirconium beads
(diameter: 1 mm) Filling ratio of milling medium: 50% by volume
Milling time: 3 hours
The mixture was centrifuged at 12,000 rpm for 20 minutes to remove
coarse particles and a dispersion solution was prepared.
Pigment-containing Example 12-Y ink was prepared by mixing the
following composition in the same manner as in Example 1, except
that the above pigment dispersion solution was used.
Pigment dispersion solution, described above 30 parts Glycerin 3
parts Diethylene glycol 10 parts Example compound 6 8 parts
Acetylenol 0.5 parts Ion-exchanged water 48.5 parts
(Preparation of Magenta Ink)
Example 12-M ink (magenta ink) was prepared in the same manner as
the Example 12-Y ink, except that Pigment Yellow 74 was replaced by
Pigment Red 122.
(Preparation of Cyan Ink)
Example 12-C ink (cyan ink) was prepared in the same manner as in
Example 12 for the yellow ink, except that Pigment Yellow 74 was
replaced by Pigment Blue 15:3.
(Preparation of Black Ink)
Example 12-Bk ink (black ink) was prepared in the same manner as
the Example 12-Y ink, except that Pigment Yellow 74 was replaced by
carbon black (Carbon black #960, Mitsubishi Chemical).
As described above, an ink set of yellow, magenta, cyan and black
inks was prepared in Example 12.
TABLE 2 Anticurling agent (Example compound Ink composition (% by
mass) No.) A DEG 1,6-HDIPA IPA Mg(NO.sub.3).sub.2 Colorant GLY Urea
AceEH Water Example 1 3 8 10 0 4 0 3(*1) 0 0 0.5 74.5 Example 2 3 8
10 0 4 0 3(*1) 0 0 0.5 74.5 Example 3 3 8 10 10 4 0 3(*1) 0 0 0.5
74.5 Example 4 2 8 10 0 4 0 3(*1) 0 0 0.5 74.5 Example 5 1 8 10 0 4
0 3(*1) 0 0 0.5 74.5 Example 6 4 8 0 10 4 2 3(*1) 0 0 0.5 72.5
Example 7 5 8 0 0 0 0 4.5(*2) 3 10 0.5 74.0 Example 8 6 8 0 0 0 0
4.5(*2) 3 10 0.5 74.0 Example 9 7 8 0 0 0 0 4.5(*2) 3 10 0.5 74.0
Example 10 8 8 0 0 0 0 4.5(*2) 3 10 0.5 74.0 Example 11-Y 6 8 0 0 0
0 4.5(*1) 3 10 0.5 74.0 Example 11-M 6 8 0 0 0 0 4.5(*3) 3 10 0.5
74.0 Example 11-Bk 6 8 0 0 0 0 4.5(*4) 3 10 0.5 74.0 Example 12-Y 6
8 10 0 0 0 30(*5) 3 0 0.5 49.5 Example 12-M 6 8 10 0 0 0 30(*6) 3 0
0.5 49.5 Example 12-C 6 8 10 0 0 0 30(*7) 3 0 0.5 49.5 Example
12-Bk 6 8 10 0 0 0 30(*8) 3 0 0.5 49.5 Comparative -- 0 10 0 4 0
3(*1) 0 0 0.5 82.5 Example 1 Comparative -- 0 0 0 0 0 4.5(*2) 3 10
0.5 82.0 Example 2 A: Anticurling agent DEG: Diethylene glycol
1,6-HD: 1,6-Hexanediol IPA: Isopropyl alcohol (*1): Yellow dye
[Acid yellow-23 (Daiwa Kasei)] (*2): Cyan dye [Direct blue 199
(Avesia)] (*3): Magenta dye [Project Fast Magenta II (Avesia)]
(*4): Black dye [Direct black 19 (Nippon Kayaku)] (*5): Pigment
yellow 74 dispersion (*6): Pigment red 122 dispersion (*7): Pigment
blue 15:3 dispersion (*8): Carbon black dispersion GLY: Glycerin
Ace-EH: Acetylenol EH (Kawaken Fine Chemicals) Water: Ion-exchanged
water
<Evaluation>
The ink prepared in each of the Examples and the Comparative
Examples was used for printing a plain paper (A4 size) on the
entire surface, except for a 3 cm margin from each edge, at a
printing duty of 100%, by using the following two types of ink jet
printers. The results are given in Table 3.
Printer 1: Ink jet printer BJC465J color head (360 dpix360 dpi,
Ejection rate: 25 pl), Canon Inc.
Printer 2: Ink jet printer BJF850 (1200 dpi.times.1200 dpi,
Ejection rate: 4.5 pl), Canon Inc.
(Evaluation 1)
Curl degree of the recording medium printed under the
above-described conditions was evaluated by the following
procedure. The printed medium was left under the conditions of
23.degree. C. and 60%.+-.5% RH for 7 days after printing, and curl
extent (vertical distance from the table on which the paper was
placed to each of the four corners) at the four corners of the
medium was measured, to calculate the average. The recording media
were NSK paper (Canon) and XEROX4024 (XEROX Corp.), both A4 in
size. The medium was placed on a table with the printed surface
upward. Curl is normally referred to as being positive when the
medium is curved concave upward, and negative when it was curved
convex. All the printed matters prepared with Examples and
Comparative Example inks curled positive.
Curl extent was evaluated according to the following standards:
A . . . Curl extent: less than 20 mm
B . . . Curl extent: 20 mm or more but less than 35 mm
C . . . Curl extent: 35 mm or more
(Evaluation 2)
Each solid image formed on the entire surface was visually
observed, to evaluate image uniformity according to the following
standards: A . . . The image is uniform, free of blurring or lines
B . . . The image is not uniform to some extent, with some blurring
or lines C . . . The image is not uniform, with notable blurring or
lines
(Evaluation 3)
Alphanumeric and solid images were continuously formed on the
entire surfaces of total of 50 sheets, and subjected to sensory
inspection for image quality, to evaluate ink ejecting stability
according to the following standards, where the sheet was A4 NSK
paper (Canon Inc.) A . . . No significant difference is present
between the image on the first sheet and that on the last sheet
with respect to ink concentration and clearness B . . . The image
on the last sheet is a little inferior to that on the first sheet
to some extent with respect to ink concentration and clearness
C . . . The image on the last sheet is low in ink concentration and
has disordered dots as compared with that on the first sheet
(Evaluation 4)
Ink stability was evaluated by observing whether or not the ink
caused problems in printing, e.g., nozzle clogging. The ink
prepared in each of Examples and Comparative Examples was used for
printing alphanumeric and solid images over the entire surface of
the recording medium after the ink had been left in a printer head
for 1 month, to observe whether the images had a disordered or
blurred portion. Recovery of the ink from solidification was
evaluated by the following standards: A . . . The image shows no
blurring. B . . . The image shows blurring to some extent. C . . .
The image shows blurring or no ink ejection.
TABLE 3 Anticurling Evaluation 1 Evaluation 1 agent (Example (one
day after) (7 days after) Printer compound No.) N-SK XX4024 N-SK
XX4024 Evaluation 2 Evaluation 3 Evaluation 4 Example 1 1 3 A A B B
A A A Example 2 2 3 A A A A A A A Example 3 1 3 A A A A A A A
Example 4 1 2 A A B B A A A Example 5 1 1 A A B B A A A Example 6 1
4 A A B B B B B Example 7 2 5 A A B B A A A Example 8 2 6 A A B B A
A A Example 9 2 7 A A B B B B B Example 10 2 8 A A B B B B B
Example 11-Y 2 6 A A B B A A A Example 11-M 2 6 A A B B A A A
Example 11-Bk 2 6 A A B B A A A Example 12-Y 2 6 A A B B A A A
Example 12-M 2 6 A A B B A A A Example 12-C 2 6 A A B B A A A
Example 12-Bk 2 6 A A B B A A A Comparative 1 -- C C C C A A C
Example 1 Comparative 2 -- C C C C B B C Example 2
* * * * *